TH Manufacturing Materials

Question 1

What is the structure of SIO2 in quartz

Answer 1

Very clear short range order

Question 2

What is the structure of SIO2 in glass

Answer 2

More jumbled structure than in quartz

Question 3

How can crystalline structures be identified

Answer 3

X-ray diffraction

Question 4

How can amorphous samples beCharacterised

Answer 4

They scatter x-rays so are more difficult to characterise

Question 5

What is a linear polymer

Answer 5

A polymer made of straight-chain

Question 6

What is a branched polymer

Answer 6

A straight-chain polymer with branch chains in each repeating unit

Question 7

What is a cross-linked polymer

Answer 7

A polymer with regular links between chains

Question 8

What is a polymer network

Answer 8

A 3-D arrangement of cross-linked polymers

Question 9

What is a thermosetting plastic

Answer 9

A plastic that does not soften upon heating as it is cross-linked

Question 10

What is a thermoplastic

Answer 10

A plastic that softens when heated and hardens when cooled

Question 11

What is silicon

Answer 11

A crystalline elemental solid

Question 12

What is silica

Answer 12

SIO2 sand quartz or glass

Question 13

What is silicone

Answer 13

I synthetic polymer

Question 14

What is the stability of
SiH
SiX
SiC
SiO

Answer 14

SiH v reactive
SiX substitution reactions
SiC quite stable
SiO v. Strong

Question 15

Is silicone thermoplastic or thermoset

Answer 15

Thermoplastic but it can be cross-linked

Question 16

How can silicone be cross-linked

Answer 16

PDMS fabrication
peroxide curing
condensation curing

Question 17

How does PDMS fabrication work

Answer 17

Polymer is heated with vinyl alkene and cross links

Question 18

How does peroxide curing work

Answer 18

Polymer with methyl branches reacts with a radical and cross links

Question 19

How does condensation caring work

Answer 19

Esther at end of polymer is hydrolysed Then undergoes SNT with another Esther at a silicon to form the new polymer

Question 20

What is curing

Answer 20

The process of forming a thermosetting plastic by cross-linking

Question 21

What are the 3 methods of silica network formation

Answer 21

Fumed
Oxidation of silicon
Sol gel synthesis

Question 22

What is the reaction equation for fumes silicon network formation

Answer 22

SiCl4 + 2H2 +O2 -> SiO2 + 4HCl

Question 23

What is the reaction equation for oxidation of silicon

Answer 23

Si + O2 -> SiO2

Question 24

What is the reaction equation for sol gel synthesis

Answer 24

Si(OR)4 + 2H2O -> SiO2 + 4ROH

Question 25

What methods can be used to characterise amorphous in soluble material

Answer 25

Microscopy Solid-state spectroscopy EDX(energy dispersive x-ray analysis) thermal analysis

Question 26

what are the 3 types of microscopy

Answer 26

light TEM SEM

Question 27

what are the pros and cons of light microscopy

Answer 27

shows colour limited by light wavelength interacts with all layers

Question 28

what is the main benefit of electron microscopy

Answer 28

much higher resolution

Question 29

what does SEM focus on

Answer 29

the surface of the subject

Question 30

what does TEM focus on

Answer 30

looking through the subject

Question 31

how does SEM work

Answer 31

electrons are accelerated towards sample beam is focused and rastered beam is scattered and observed

Question 32

how does TEM work

Answer 32

electrons are accelerated towards sample electrons are focused as in light microscopy transmitted through sample observed via fluorescence or detectors

Question 33

how can TEM results be analysed

Answer 33

few electrons pass through heavy metals - appear darker

Question 34

which electron microscopy gives higher resolution

Answer 34

TEM

Question 35

what is a requirement of TEM

Answer 35

thin sample

Question 36

give an effective way to determine composition

Answer 36

energy dispersive x ray spectroscopy

Question 37

how does energy dispersive x ray spectroscopy

Answer 37

uses high energy elections to eject inner electrons higher energy electron drops in energy to fill gap x ray is released frequency indicates atom

Question 38

what factors should be considered when analysing elemental composition

Answer 38

incident electrons must have enough energy | needs ideal sample to give quantitative results

Question 39

what happens in electron diffractions

Answer 39

electrons interact with electron cloud atoms

Question 40

how does the structure effect electron diffraction results

Answer 40

sharp ring - crystal | broad ring - amorphous

Question 41

how are samples prepared for SEM

Answer 41

dry deposited onto sticky carbon tab insulating material is covered in conductive coating

Question 42

how is a sample prepared for TEM

Answer 42

sample placed on a supporting grid - usually copper

Question 43

what is a microtomy

Answer 43

device for cutting thin sections of a material